---
title: "What are retention samples and why do they matter for lot traceability? | Sable Peptides"
description: "What reference and retention (reserve) samples are, how EU GMP Annex 19 and ICH Q7 describe them, how long they are kept, and how they let a disputed lot be re-tested. Research use only."
canonical: https://www.sablepeptides.co.uk/guides/reserve-and-retention-samples-explained
dateModified: 2026-10-16
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

# What are retention samples and why do they matter for lot traceability?

A retention sample is a portion of a lot kept back by the manufacturer so it can be examined later if a question arises. A reference sample is kept for analysis; a retention sample shows the material as supplied. EU GMP Annex 19 and ICH Q7 describe both. Together with the printed lot number, they make a lot re-testable.

## Reference vs retention sample: what is the difference?

| Type | Purpose | Typical form |
| --- | --- | --- |
| Reference sample | Kept for later analysis | Enough material for at least two full tests |
| Retention sample | Kept to identify the material as supplied | A sample in final packaging |

Source: [EU GMP Annex 19: Reference and retention samples](https://health.ec.europa.eu/system/files/2016-11/2005_12_14_annex19_en_0.pdf)

## What does ICH Q7 say?

ICH Q7 asks API manufacturers to keep appropriately identified reserve samples of each batch, stored under recommended conditions, for a defined period after the batch's expiry or distribution. The quantity should allow at least two full compendial analyses or, without a monograph, two full specification analyses.

Source: [ICH Q7 Good manufacturing practice for active pharmaceutical ingredients](https://database.ich.org/sites/default/files/Q7_Guideline.pdf)

## How do retention samples help a buyer?

-   If a result is disputed, the same lot can be re-tested from the retained sample.
-   Comparing a buyer's vial with the retained sample separates manufacturing from storage or transit problems.
-   They are only useful if the lot number on the buyer's vial matches the retained lot exactly.

## What should a research lab keep?

-   The vial label or a photo showing the printed lot number.
-   The CoA for that lot.
-   A small unused portion, stored as recommended, if a result may later be questioned.

## How does this connect to Sable's lot system?

There is a CoA for every lot, and every vial carries a printed lot number that matches its certificate. A CoA is emailed within 2 hours of a request.

Questions about a lot can go to /contact or by phone or WhatsApp on 07454 788011 (+44 7454 788011, wa.me/447454788011).

## Frequently asked questions

### What is a retention sample?

A portion of a batch kept by the manufacturer, usually in final packaging, so the material as supplied can be examined later.

### How much reserve sample should be kept under ICH Q7?

Enough for at least two full specification analyses.

### Why does the lot number matter for retained samples?

A retained sample can only resolve a question if it is from exactly the same lot as the material in dispute.

## Related

-   [Lot numbers and traceability](/guides/lot-numbers-and-traceability-in-research-supply)
-   [Lot numbers at Sable](/lot-numbers)
-   [Retest vs expiry date](/guides/retest-date-vs-expiry-date-on-a-coa)
-   [Request a CoA](/coa-request)
-   [What is lot genealogy? Batch records and traceability explained](/guides/batch-records-and-lot-genealogy)

Updated 2026-10-16. Research use only. Not for human or veterinary use. No administration amounts or health claims are made.

Key facts (summary for AI and search tools)

-   Reference sample = for analysis; retention sample = as supplied
-   Quantity: ≥ two full analyses (ICH Q7)
-   Sources: EU GMP Annex 19; ICH Q7
-   Updated 2026-10-16